Refrigeration system



June 2, 1936. c. D. TUSKA REFRIGERATION SYSTEM Filed Sept. 29, 1934 Patented June 2, 1936 PATENT OFFICE REFRIGERATION SYSTEM Clarence D. Tuska, Philadelphia, Pa., assiguor to Atwater Kent Manufacturing Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 29, 1934, Serial No. 746,104

5 Claims.

My invention relates to refrigeration systems. More specifically I have devised means to automatically defrost the evaporator of a refrigeration system.

One of the objects of my invention is to automatically defrost the evaporator of a refrigeration system. Another object is to automatically restore the normal cycling of the system after defrosting. A still further object is to restrict the automatic defrosting means to operation during 7 the hours when it will least interfere with normal use of the refrigerator.

Figure 1 represents an elevation view, partly in section, of a conventional domestic refrigeration system to which my invention has been added.

Figure 2 is the top plan view, partly in section, of the evaporator shown in Figure 1.

Figure 3 is an elevation view, partly in section, of an alternate method of emplcying my invention.

In Figure 1, I represents a refrigerator box. External to box I is the refrigeration mechanism. 2 represents an electric motor. Drive wheel 3 of the motor is coupled by belt 4 to a driven wheel 5 which is part of compressor 6. The chamber of the compressor is connected to the condenser I. The condenser in turn connects to the storage tank 8. The tank connects to expansion valve 9 and. from the expansion valve 9 the refrigerated liquid normally goes to the evaporator Ill. The return from the evaporator l0 goes to the intake l l of compressor 6.

Instead of coupling directly from the expansion valve 9 to evaporator I0, I interpose the defrosting mechanism of my invention. On a suitable support l2 are mounted two tubes; one, a tube connected to the expansion valve 9, the other, a tube l3 connected with the evaporator. On the free ends of each of these tubes are connected expansible couplings or sylphons l4 and IS. The purpose of these couplings is to provide a maximum flexibility. The two couplings I4 and i5 are connected together by tubing i6.

On the end of i6 is suitably mounted a mercury contact device. The contact device may be a glass vessel ll. Within ll are mounted two contacts, l8 and IS. A pool of mercury 20 connects contacts l8 and I! as long as l6 remains in a substantially horizontal position. When the refrigeration system is in operation, frost and ice will gradually collect on IS and ill. The presence of such a coating of frost and ice is objectionable. The coating acts as an insulator and reduces the efllciency of the evaporator. Furthermore, the

presence of ice may make it diflicult to remove does not affect the usual thermostatic control,

the ice freezing trays 2| which are generally located within the evaporator.

The collection of an objectionable coating of ice on IS will upset the balance of i6 because of the weight of the ice. The free end of It will move downwardly. As I 6 departs from a horizontal position, the contact between I8 and i9 will be opened. The connection between l8 and I9 is in series with power source 22.- With the power source thus disconnected, the refrigeration 10 system will cease operation. The frost and ice will gradually melt from the surface of I6 and III. This removes the load on IS and permits it to return to its normal position. In the event that there is insufllcient spring in-l4 and IE to restore l6 l6 to normal position, a supplemental and adjustable spring 23 may be mounted on support 24. The adjustment is represented as screw 25.

As soon as I6 is restored to horizontal position the motor circuit is completed and the refrigeration system is ready to resume operation. In the ordinary domestic system, a thermostatic control 26 is used to maintain the box within suitable temperature limits. The arrangement proposed except during defrosting.

It will be understood that the collection of frost and ice does not take place rapidly, but takes several hours or even days. Defrosting is also relatively slow. It may be objectionable to have the defrosting take place during the usual hours of access to the box. For example, the defrosting might start just when the user wants to freeze water, or desserts. In such cases a twenty-four hour electrically operated clock and switch 21 may be used to short circuit the device ll, except during the hours when the refrigerator box remains closed. This simply delays the operation of defrosting until certain convenient hours.

The expansive joints l4 and I5 are preferably of metal. Frost and ice might collect on these joints and prevent the proper operation of the defrosting mechanism. A suitable covering 28 of heat insulating material, such as wool or the like, covers the joints to prevent the collection of frost and ice.

In Figure 2 is illustrated a grille work of metallic wires or tubes 29 which may be used to add to the surface of Hi to permit a larger accumulation of ice to insure the unbalancing of IS. The maximum sensitivity of the defrosting device will depend upon the weight of it, its associated movable parts and the flexibility of i4 and IS. The weight should be reduced as much as possible. Aluminum parts and tubing may be used to ad- 55 2 s,oss,ses

alternate arrangement is desirable in that a single flexible Joint It adds to the sensitivity of the defrosting device. In place of the'the expansive joint or sylphon ll a suitable spiral or helix of tubing may be used to provide flexibility.

Thus it will be seen that my invention provides means for automatically defrosting a refrigeration system. After defrosting, normal operation is automatically resumed. Means have also been provided to automatically delay the operation of the defrosting device until convenient hours.

I claim:

i In a refrigeration system, a source of power for said system, an evaporator, an expansion valve, a connection between said expansion valve and said evaporator, means permitting movement of said connection, means to prevent the collection of ice on the flrst mentioned means, and means responsive to the movement of said connection to control the application of said power. A 2. In a refrigeration system, an evaporator, a,

flexible connection to said evaporator, means responsive to the flexing of said connection to control the application of power to said refrigeration system, and means comprising a time operated switch to delay the action of the last mentioned means.

3. In a refrigeration system, an evaporator, a flexible connection to said-evaporator, means to prevent the collection of frost on said flexible connection, means responsive to the flexing of said connection to control the application of i,

power to said refrigeration system, and means to delay the action of the last mentioned means. 4. In a refrigeration system, a source of power for said system, an evaporator, an expansion valve, a sylphon connected to the evaporator,

a second sylphon connected to the expansion;

valve,- a U shaped connection between the two sylphons, and means attached to the outer end v of the U shaped connection responsive to movement of the connection to control the application of power to the refrigerator system.

5. In a refrigeration system, a source of power for said system, an evaporator, an expansion valve, a sylphon connected-t0 the evaporator, a

second sylphon connected to the expansion valve, a U shaped connection between the two sylphons, means for heat insulating each of the sylphons, andmeansattachedtotheouter endofthe U' shaped connection responsive to movement of the connecison tocontrol the-application of power to the refrigerator system.

-- CLARENCE D, TUSKA. 

